This invention relates generally to methods and apparatus for holding and delivering molten nonferrous metal to a shot sleeve and/or a pour cup of a casting machine. More specifically, it relates to a method and apparatus for holding within a dosing furnace a predetermined volume of molten nonferrous metal by means of a specialized holding chamber, which holding chamber facilitates the pressurized delivery of molten metal for filling a shot sleeve, pour cup, mold, casting or the like. It also relates to a holding chamber which may be functionally adapted to be readily removable from the dosing furnace to facilitate cleaning of the holding chamber.
In the area of furnaces used for melting and holding nonferrous metals, it has long been recognized as advantageous to provide integral apportioning devices within such furnaces for the removal of predetermined volumes of molten metal from the furnaces. In this fashion, the volume of molten metal which is removed can be controlled. Uniformity in pours can also be achieved. Typically, such an apportioning device uses a compressed gas to force a predetermined amount of molten metal from a reservoir to a delivery means. The gas most often used for this purpose is nitrogen. Nitrogen is inert with respect to nonferrous molten metals such as aluminum.
In the experience of this inventor, one problem encountered by the use of such dosing chambers is the fact that they are difficult to clean, repair and/or replace if such is desired or required. The cleaning of such a dosing chamber requires the complete emptying of the contents of the furnace and a relatively long cooling off period for the furnace. This creates down time for the furnace which is not practical or efficient in a high volume production setting.
It is, therefore, a principal object of this invention to provide a new, useful and uncomplicated method and apparatus for accurately delivering predetermined amounts of molten metal as such metal is desired or required. It is a further object of this invention to provide such a method and apparatus which requires only a minimal number of elements and which requires only a minimal number of steps to utilize. It is yet another object of this invention to provide such a method and apparatus which can readily used in a variety of furnace configurations. It is still another object of this invention to provide such a method and apparatus which provides for a readily removable dosing chamber which is adaptable to be usable within a variety of new and existing furnaces which are commercially available. It is still another object of this invention to provide a dosing chamber in accordance with the method and apparatus of the present invention which is not formed as an integral part of the refractory lining of a furnace. It is still another object of this invention to provide such a method and apparatus which may provide for a removable dosing chamber which can be used and reused over and over again.
The present invention has obtained these objects. It provides for a dosing chamber which may be insertable within and removable from the metal holding chamber of a molten metal furnace. The dosing chamber of the present invention is not formed as an integral part of the refractory lining of the molten metal furnace. The dosing chamber of the present invention also includes a chamber shell having a gas inlet port and a molten metal discharge port. The gas inlet port is functionally adapted to sealingly receive a gas stopper tube within the port. With a pressurized inert gas introduced through the gas stopper tube, molten metal contained within the dosing chamber is force out of the discharge port and up and into a metal receiver. The dosing chamber method and apparatus of the present invention is functionally adapted to be insertable within a variety of commercially available furnaces. The dosing chamber method and apparatus of the present invention may also be functionally adapted to be readily removable from the molten metal chamber such that the dosing chamber can be removed and cleaned as such is desired or required. The foregoing and other features of the method and apparatus of the present invention will be further apparent from the description which follows.